Gyroscopic apparatus



y 8 195 w. L. TRACY 2,602,334

GYROSCOPIC APPARATUS Filed Jan. 5, 1946 2 SHEETS SHEET l mvemon A/JLLl/IM L Patented July 8, 19:52

GrRoscoPIo APPARATUS William L. Tracy, Port Washington, N. Y., assignor to The Sperry. Corporation, a corporation of Delaware Application January 3, 1946, Serial No. 638,858

ments such as particularly employed in gyrosoopic artificial horizons.

The invention in the present application developed from a situation demanding a small compact pneumatically driven and erected attitude gyro. Heretofore, it had been considered virtually an impossibilityto construct an instrument.

the same size as other non-gyroscopic flight instruments without sacrificing reliability, accuracy of its readings, and the quality of other required features of a gyro vertical.

Due to the very nature of the rotor propelling force and the necessary general plan of the small gyro instrument contemplated, it was discovered that spurious air torques were imposed upon the rotor case since the erecting jets were located quite near the inside of the instrument case, as one structural cause. Even though the erection jets were placed as far away as possible from the case, a suitable subject instrument seemed to be unattainable. It was finally found that since the instrument case fitted snugly around the gyro itself, the direct blast'of air from the erection jets against the case was deflected by the curvature of the case against the rotor frame and the gimbal ring.

One feature of this invention is the provision of means for overcoming the above difficulties.

Another feature of the present invention is the provision of a small instrument of this type, that is, in effect, completely maneuverable, or in other words, an instrument in which the rotor case of the gyro vertical andits gimbalare both provided with substantially360 of freedom about the respective axes of its universal mounting.

A further feature of the invention isthe pro- 9 Claims. (01. 74 5.43)

vision of a gyro shellcapable of preventing a phase of spurious, air reaction torques.

A further feature of .theinvention is the provision of specially shaped pendulous shutters acting with minimum'reaction with dispersion characteristics which prevent another phase of .undesired air reaction in the gyro system, 'and which further eliminate the previous necessity of close mechanical tolerance between the deflectors or shutters and the jets :or orifices ofpast erection devices.

A further feature of the. invention isthe pro vision of an outer'casin'g or shell not only having the abovecharacteristics but. also being suitable for the placement thereon of craft attitude indicia. I

A still further feature of the invention lies in the design of suoha shell which is capable. of

This invention relates to gyro vertical instrurapid demounting when servicing ofthe gyrovertical is desired. v The invention in anotherof itsaspects relates to novel features of the instrumentalities described herein for achieving the principalobjects of the invention and to novel principles employed in those instrumentalities, whether. or not these features and principles are used for the saidprincipal objects or in the said field.

A further object of the invention is to provide improved apparatus and instrumentalities embodying novel features and principles, adapted for use in realizing the above objects and also adapted for use in other fields.

Other objects and advantages of this invention will become apparent as the description proceeds.

In the drawings,

Fig. 1 is a front elevation of an instrument constructed in-accordance with the present invention; I

Fig. 2 is a side elevation of the instrument shown in Fig. 1, with the case thereof in section;

Fig. 3 is a detail front elevation of the instrug ment of Fig. l, devoid of its case mounting, plate, and the gyro shell being shown insection;

Fig. 4 is an enlarged. detail frontv elevation of the subject instrument taken in section on the line 4-4 of Fig. 2;

Fig. 5 is a front elevation of one pair of shutters of the erection system in the subject instrument pivoted about an axis paralleling the gimbal axis;

Fig. 6 is a front elevation of a second pair of shutters of the erection system pivoted about a horizontal axis atright angles to the above first axis and in the same plane;

Fig. 6a is an enlarged cross section view on line 6a6a of Fig. 6, showing the shutter or deflector construction;

, Fig. '7 is a side elevation of the pendulous shutter structure in Fig. 5;

Fig. 8 is a plan View of the structure in Fig. 5;

Fig. 9 is a side elevation of the pendulous shutter structure in Fig. 6, showing the uppe fportions offset to clear bearings on the gimbal arms;

Fig. 10 is a plan view of the pendulous shutter structure in Fig. 6; and

Fig. 11 is a perspective view of a three-piece stirrup-shaped frame similar to the structure ofFig.6. I V p With particular reference to Figs. 14, the gyroscopic instrument constructed in accordance with the present invention is shown to include an pendulous shutter outer case or casing H3 having a window H in the front wall thereof. The case It has a tubular extension 13 at the rear containing such items as an air'filter and a long bearing of the character described in copending application Serial No. 640,665, filed January 11, 1946, by William L. Tracy, now Patent No. 2,504,166, for an improved shaft' and gimbal mounting structure. The herein shown forked gimbal ring 14 is thus free to turn through 360 about the axis AA which is parallel to the fore-and-aft axis of the craft. Within the gimbal ring M there: is journalled the rotor case l5 by means of pivots l6, I! supported in conventional ball bearings not shown. The rotor case 15 is free to undergo substantially a complete revolution relative to the gimbal ring 14 about the axis BB defined: by the pivots I6, I! which is perpendicular to AA and is normally horizontal. A complete revolution is prevented by stop pins (not shown) placed on the enlarged part of these pivots and on the inside of the instrument case- Hl'. A rotor l8 spins in bearings 80 about a substantially vertical axis CO in the rotor case [5.

The rotor case [5 encloses the rotor l8 and is air-tight except for a drive nozzle and a plurality of orifices or air jets 25, 25, 25 26" ofan air erection system. I

Rotation of the rotor I8 iseffected by exhausting air continuously from the interior of the instrument case' through a suction hose 2| connected to a conventionalvacuum pump in a manner, generally speaking, similar to that used in the structure of the Patent No. 2,190,698 to Carter. The rotor is driven by atmospheric pressure since air impinges upon its buckets. The air reaches the buckets in the rotor by way of an exteriorly facing filter (not described) in tubular' extension 13' via a conventional split gimbal bearing therein and a hollow gimbal arm leading to drive nozzle 20. After the onrushing air is spent considerably within the rotor case, it is bled away from thesame through eight orifices groupedin' pairs marked 25', 2 5 and 2'6, 26' found in the-bottom of the special rotor case [5 now to be described. Orifi'ces 25" are not shown in the' drawings but are'paired' with orifices 2-5 inthe same relationship as orifices 25, 25' and therefore are situated in the bottom rear ofthe rotor case, as viewed in Fig. 3-. These orifices are also called jets.

In order to derive a maximum moment arm from the air reaction of these jets or orifices special consideration hadtobe given to the overall construction of the rotor case [5. This case 15 comprises a substantially central cylindri'cally shaped body portion 30 The top of cylinder 39 is joined to a protruding body 3| formedto retain special rotor bearing parts not the subject of this invention. Since the size of the subject instrument was restricted to have dimensions, when viewed as placed in an aircraft instrument panel board, comparable with the rest of the flight instruments, it was necessary to enclose all moving parts within a compact, preferably cylindrical, instrument case Illa It is desirable to con struct the rotor case and associated parts in such a way that the instrument system is mounted in neutral equilibrium or is slightly pendulous, and maximum erecting force would be created for a minimum gyro tilt of about 2. With these points in mind, further details of the rotor case 15 are set forth. The weight of this rotor case was decreased by forming its central bottom part into a well 32 having provisions for special bear ings featured in another application. The well 32 provides a chamber for receiving the air passing from the buckets of the rotor. By joining the inverted well 32 to the cylinder 30 with a sloping portion such as an inverted truncated cone 33, the limitations of pendulum action,

weight and instrument case clearance discussed above is ultimately satisfied. Since; effective moment arms from air reaction in the instrument system described thus far can only be attained with sufiicient reliability when the air jets or orifices are oriented in a perpendicular relationship to the axis about which erection is to take place, the orifices 25, 25' and 26, 25 must be obtained by small horizontally drilled holes within the conical portion 33 of the rotor case 35. Theutilization oftwo vertically aligned horizon.-

tal holes 25 or 25 associated with one axis as a AA", BB) and areso designed that air issuing from them when theorifices are uncovered exert equal and opposite reaction torques about the axis AA, while neither'exerts any torque about the axis BB. Similarly; the orifices or'j'et's 26, 2t" are spaced. at equalv distances fore and aft from; the center" of the gyroscope and are so designed that the airissuing. from. them when the orifices are uncovered. exert equal and opposite reaction torques about'the'axis BB, while" neither exerts any torque about the: aXlSTAA'. It follows that if: all the jetsv or orifices are: uncovered, the reactions they exert on the rotor case 15 are balanced, since each". jet is balanced by an equal and oppositely acting stream of air.

The laterally spaced jets 25-, '25" are variably controlled by means-of shutters 35, 35", which form part of 'aipend'ulousstirrup-shaped shutter frame 36' and which variably intercept the jets 25, 25' in accordance with the tilt of rotor case |5- relative to the shutter frame 36. The frame 36 has. bearing holes 36 in the upper portion of each of. its arms. Therotor case has, at its upper portion, a pair of pivots 38.; 38" for engaging the bearing holes 35' of the frame 36, the axis of pivots 318, 38" being parallel to the axis BB of the rotor case. Frame 36 has apair of exteriorly' facing leaf spring members 31' anchored at one end to the frame and having its free end adjacent the bearing: holes 36'. The leaf spring members 37' are for the purpose of preventing lateral movement of the frame 36 on its pivots: 38', 38". Inthe normal relative. position of the rotor case I5 and the pendulous shutter frame 36 shown in Figs. 2 3 and 4 which is that taken up, for example, when the axis of the rotor 18 is vertical and the shutter frame 36' is hanging freely under gravity and when no acceleration forces are effective thereon the shutters 35, 35" intercept the jets 25, 25" to equal extent, viz'., they intercept substantially one-half of each jet. If this positicn is disturbed, e. g., by tilting of the gyroscope about the transverse axis BB (pitch) as shown inFigs; 2 and 4,. one: of the jets 25, 25" is uncovered by its shutter 35 or 35' toa greater'extent than normal and the other to a less extent, with the result that an unbalanced air jet reaction. is applied to the: rotor case. This unbalanced air jet reaction applies a torque to the rotor case uppermost place in the central body 30 of therotor case and the associated orifices are vertically aligned with the shutter, a minimum shift of the rotor axis from a substantially vertical normal position creates a maximum erecting correction force. As a matter of fact, a 2 tilt of the gyro housing or shell unbalances the described air erecting system to such an extent that full and substantially. immediate correction of same takes place.

However, the described erecting system caused errors in the reading of the instrument since not all the air bled from the rotor case l5 by the orifices described was under the influence of the proper guiding means. Some of the air became trapped above and around the gimbal arms of the gimbal ring M to create adverse couples within the instrument. It is not necessary to go into detail on the causes of these couples. This dimculty is partially remedied by completely enclosing the rotor case |5 with a gyro shell 45 in the form of an oblate spheroid preferably made in two sections 46, 41. which are joined on a horizontal plane. These sections are cut or tailored along the flattened portions, as shown in Fig. 4

to fit around the enlarged part 48 of the pivots l6, H which are fastened to the rotor case |5 by convenient means such as machine screws 49. Consequently, shell 45 is detachably fixed to the rotor case |5. Exhaust ports such as holes 50 are provided in the shell 45in its lower section 41 opposite the paired orifices 25, 25' and 26, 26' for the purpose of bleeding air away from the space between the shell 45 and rotor case |5 including the space formed by the well 32. Additional holes |9 are provided in the top of shell 45 as indicated in Fig. 4 to prevent air pressure from building up within the shell.

Of course, now the gyro shell 45 turns with the rotor case and since it has a. smooth contour it is subject much less to air turbulence than the irregular rotor case as it functions in aircraft undergoing all sorts of maneuvers. Test data on this gyroscopic instrument shows an increase of pitch erection torque of about 40 per cent and roll erection torque of about 25 per cent when the shell 45 and a screen 82 on the inside surface of the instrument case (not a part of this invention) is incorporated therein. Selected circumferential portions of the shell 45, as seen in Fig. 1, are marked with indicia such as spaced, short normally horizontal markings 55 disposed as a whole vertically when viewed in front of the instrument panel. These markings indicate the pitch attitude of the craft and since the gyrovertical is constructed as described for ascertaining even craft attitudes in complete loops and rolls, it is desirable to paint or enamel the normally lower half portion 41 of the shell 45 in a color contrasting favorably, optically speaking, from the upper half portion 46 to give an unfailing indication to the pilot whether he is approaching an upside-down flying position. Other markings 56 similar to geographic latitude references on a globe are spaced on shell 45 which 6 can be oriented with the fixed horizontal indicia 60, 6| on the face of the gyro-vertical seen in Fig. 1 to give a pilot his position in pitch maneuvers. Also, a meridian line 62 on the shell'45 is compared with a-fixedindex 63 that is a part of a bank scale 64'to provide the pilot with an indication of the attitude of the craft on which the instrument is used about its fore and aft axis.

Thus, it is seen that the two-part shell 45 is viewable from a substantially universal observation standpoint.

Another consideration in the construction of thesubject gyroscopic' instrument involved the problem of high and variable rotor back-pres sure from the various jets due to unequal initial tolerance between the face or body of the jets and the associated deflector and that due to unequal normal wear of the bearings supporting the deflectors. Unequal backpressure from the various orifices or jets when a normal and balanced air flow from all jets was supposed to exist caused the rotor and its case to be influenced by an initial adverse couple or erection thereby giving an incorrect instrument reading. This condition resulted in greater error as the jets involved in this action were blocked or valved by the previously designed valves in the course of erecting actions.

Hence, further study of the: pendulous shutters and specifically the deflectors associated with the stirrup-shaped frames 36and 4| appears to be necessary. First, it can beiseen in Figs. 2, 4 and 9 that the upright arms of the stirrup-shaped frame 36 are curved around the bosses 48 of the pivots I6 and I! so that the frame can swing freely through a small angle about the pivots 38, 3B withoutfouling the pivot bosses. x

The extent of the possible angular movement of the frames 36 and 4| about the pivot axis 38, 38' and 65, 65', respectively,relative to the rotor case I5 is limited by protruding means integral with the case such as stops 66 and 61.

Now that the mounting means for the deflectors 35, 35' and 40, 40' have beenthoroughly discussed, the specific features of the novel deflectors themselves can be revealed immediately by referring to Figs. 5 and 10. Complete discussion of all the deflectors is unnecessary since all'deflectors are alike. They are peculiarly characterized by a knife-like appearance such as shown clearly in Fig. 6a. which is a detail'section of deflector'35. The fairly sharp side or knife-edge l2 normally is substantially aligned with the per-' pendicular center line of the two associated orifices which in this showing are orifices 25 seen in Fig. 4. Knife-edge I2 is offset from the contiguous body portions of the frame 36 in a manner shown in Figs. 9 and 10. The flat face of each deflector is held away from the face or surrounding body of each orifice by a properseparation'of the upright arms in frames 36 and 4| and this sep-' aration is maintained with the aid of pivot springs 31. Also, the knife edge which is integral with each deflector is offset from contiguous portions of the pendulum to'aid in providing a substantial clearance between the knife-edge and the orifices'.

These deflectors are 'so further formed and hung from their associatedstirrup frame that they intersect the jets of air from the orifices at an oblique angle, thus the spoiled air from the orifices is directed to interior positions of the shell 45 or so as' to .miss theholes 56 of the same. For example, the deflector, or shutter 35 inLframe tit-shown in Figs-.4 8J11d-6};i5. at an angleto its. upright. supports, and: thereby it i is madeparallel: to; the surface" of the;.truncated :cone .33. The. oppositely disposed; knife-edge portions are relatively inclined at. aadiverging; oblique angle toward the; spacedfverticalshutter arms; Air

indicated byithe line "I 80; leaving. the: orifices shown: strikingsthe. exposed". portion of deflector having k'nifeeedge .12; is:directed for: the-most partupward'interiorly'ofithe'hole 50: v

Thus, the deflectors really act-torspoiltheair from' therjets. when they: are: not-supposed. to produce erecting" torques. However, when any jetxis produced-Jae. the'-' result of exposing ,more than one ThaIfTOf'; the'associated'orifice; the-spoilingg elfect of "the deflector-'isrnon existent for theipartiof theorificeewhih. is not blocked; 1

It may berfurther. desirablertorprovide. adjust? ment: meanssgin-i the stirrup frames" 36 and 41 for changing: the characteristics-of its pendulum action:- Thisis: done as. shown in Fig; 11 by making the paired deflectors from onecross member or; element 10- and joining; its upright endsto arms", or: uprights I I: and -12kby adj ustable meansrsucli as machine screws:'l3"'and slots 14, respectively: Arms'll and 12' arerformed-in' the lower portion with inwardly'facing" grooves or slots 75 and 16, respectively, ini-whichi the coactingI-endsof the crossim'ember .16: can slide when: the screws?- '13 are: loosenedi ini: drilled and tapped holes in: the: crossmember; 10 opposite thelslots". I

The above describedi arrangement can also aid in compensating for bearing wear at pivots 38; 38' and 65, 65 and thus further adjustthe vertical position of all the deflectors-"described; While the. added improvement has been shown in the drawing as being directed to a specific :type of stirrup-shaped frame, it is to be understood that it can be u sed with a -va riety of frames orpendulous' shutters.

Since many changes couldbemade in the above construction and many'apparently wide- 1y different embodiments ofithisrinvention' could be. made without. departing, from the scope thereof, it is intended thatall'matter contained in the above -descriptionror. shown in the accompanying drawings shall: be interpreted as illustrative and not in a limiting sense.

What is claimed is: i

l. A gyro-vertical comprising; a gyro rotor, a rotor bearing case having an inwardly sloping bottom portion, a gyro shell; means for supporting all of the same: for oscillation about horizontal axes in substantially neutral'equilibrium and. with the rotorhaving a normally vertical spin. axis; gravitationally responsive means for maintaining said spin axis erect including a plurality of'pairsof opposed orifices normally-horizontally positioned at' said' bottom portion emittingv jets chair and adaptedqthereby to exert erectingitorques'on said rotor case about either of'said horizontalaxes, and a plurality of pairs of" pendulous shutters. pivotally; suspended: from theupper'part' of the: case, each pair of said sh'uttersformingpart of a stirrup-shaped frame extending around the'lower part .of said case, a lower side of each one of said pendulous shutters having a knife-formed portion-adjacent to said sloping,,bottoimportion and being displaced outwardly initially'from: each of said orifices to spoil the jets issuing. from said orifices and-to ultimately create anvair deflection action for altering;- the: relative. strength I of said" torques abouteither one. otsaidaxesnpon relative inclination. of said means land-said case about the other. of said axes; said gyro shelibeinganoblate spheroid formed-from. two parts joinedat a hor-- izontal plane and having openings opposite said jets, said shutters intersecting each of said jets at 1 an oblique angle: whereby the spoiled airsissubstantially directed to portions surrounding said: shell openings .zinteriorly of the. same and whereby erecting action can takepl'aceonly when the shutters are in a.position.to' permit above normal air flow outzofthe openings in thegyro shell.

2; The combinatiozfinan air erected' gyroi vertical of, a universally mounted rotor-bearing case with an exterior portion in the form of a generally spherical shell having pitch and roll indicia thereon" and with an interior portion having a lower part" exteriorlyshaped in the form of an'inverted truncated bone, a pair of oppositely disposed horizontal ports in the lower part of said interior portion of the case and a pair of adjacent ports in said shell from which jets of air normally issue to exert equal and opposite torques about one of'the axes of uni versal mounting: of the case, and a pendulous shutter for differentiallyintercepting the jets of air pivotally mounted'on said case to depend below the lowerpart of the interior 'portioh'=-there0f, said shutter including knife blades situated -b'\.'-- tween the ports in the exterior andinterior'portions'of said 'caseand'arranged in spaced 'paral-- lel relation to the'in-verted' cone shapedpart' of said case. 1 a

3. A gyro vertical a'sclaimedin-claim 2', in which said shell includesports in its upper per-- tion.

fl. The combination in an air erected gyro vertical of,-a universally mounted rotor-bearing case having a-closed lower part 'exteriorly shapecl in the form ofan inverted' truncated' cone, a pair of opposit'elydisposed horizontal ports in said'lower part froin which 'jets of' air normally issue to exert equal "and' opposite torques about one of the axes of universal mounting of thecase, and a pendulous shutter for differentially intercepting the jets-of air pivotally mounted on said case, said-shutter depending below the case and including k nife' blades adjacent the respective ports "arranged in spaced parallel relation to the inverted truncated cone shaped part of said case. r

5: In an air erected gyro vertical, a rotor case having two pairs:ofoppositelydisposed ports at rightangles to one another iromwhich erecting jets of air issue, a. firstv pendulum depending from the exteriorrof saidlcase having knife edges respectively situated in the plane ti and at an oblique angle to the air jets: from one of. the pairs-cflports, and a second pendulum depending from the exterior of said case at right angles to said first'pendulum havingl knife edges respectively situated in. the plane of and at an oblique angle to theairi jets from, the other oil the pairs of ports.

6. In an air erected-gyro vertical, a rotorbearing case having an" attitude indicating shell of generally spherical shape; said" shell having four openings in the bottom thereof and two openings in the top thereof.

7. In an air erected gyro vertical, a rotorbearing case having i a bottoml exterior portion formed inthe shape of an inverted truncated cone, said portion having two mutually" P81136114 dicular pairs of horizontal openings in the conical surface thereof.

8. In an air erected gyro vertical, a pendulous shutter having two spaced vertical arms and a bottom part connecting said arms having two straight, oppositely disposed, knife edge portions inclined at a diverging, oblique angle toward sai vertical arms.

9. In an air erected gyro vertical, a rotor case having oppositely disposed ports therein from which jets of air issue, and a pendulous shutter pivotally mounted on the exterior of said case having two spaced vertical arms and a bottom part connecting the arms having two straight, oppositely disposed, knife edge portions inclined at a diverging oblique angle toward the vertical arms, said shutter being so constructed and mounted that the knife edge portions thereof differentially intercept the air jets upon relative tilt between the shutter and case.

WILLIAM L. TRACY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,324,482 Titterington Dec. 9, 1919 1,518,892 Bates Dec. 9, 19:24 1,726,643 Borresen Sept. 3, 1929 1,939,825 Narvesen et a1 Dec. 19, 1933 2,183,939 Moss Dec. 19, 1939 2,249,744 Carter July 22, 1941 2,278,913 Carter Apr. 7, 1942 2,344,126 Carlson Mar. 14, 1944 2,365,439 Schulze Dec. 19, 1944 2,366,543 Meredith Jan. 2, 1945 2,368,058 Whatley Jan. 23, 1945 2,373,120 Kenyon Apr. 10, 1945 2,390,532 Haskins, Jr., et a1. Dec. 11, 1945 2,395,251 Carlson Feb. 19, 1946 2,420,674 Moore et al. May 20, 1947 

